1. Field of the Invention
The present invention relates to a piezoelectric device system; more particularly, the present invention relates to a piezoelectric device system producing both vibration and electric power.
2. Description of the Related Art
The piezoelectric effect refers to conversion between electrical energy and mechanical energy. The direct piezoelectric effect was first discovered in 1880 by the brothers Pierre Curie and Jacques Curie. In 1947, the discovery by S. Roberts of the effect of a direct current electric field on the remanent polarization of Barium Titanate (BaTiO3) ceramics inspired research into the piezoelectric properties of ceramic materials and their possible applications.
The direct piezoelectric effect is the process of converting mechanical energy into electrical energy. When physical pressure is applied to a piezoelectric material, the electric dipole moment of the material is shortened due to the compression. At this time, in order to resist this change, the piezoelectric material generates equivalent positive and negative charges on a corresponding surface of the material so as to maintain its original shape. The generation of polarization due to deformation is called the “direct piezoelectric effect”.
The inverse piezoelectric effect is the process of converting electrical energy into mechanical energy. When an electric field (voltage) is applied to the surface of the piezoelectric material, the electric dipole moment is elongated due to the electric field effect, so the piezoelectric material extends along the direction of the electric field in order to resist this change. The generation of mechanical deformation by an electric field is called the “inverse piezoelectric effect”.
In general, a piezoelectric element is commonly applied for simply converting mechanical energy into electrical energy, or for converting electrical energy into mechanical energy. However, since the piezoelectric element can utilize a voltage to generate vibration, and can further utilize the vibration (for causing deformation) to generate electric power, a system can be designed with two piezoelectric elements, wherein one is used as a vibration source, and the other is used as a power source, such that various applications can be implemented by utilizing the vibration property to generate electric power.